All-metal manifolds are widely used in UHV vacuum systems to interconnect system components such as emitters and detectors, vacuum lines, and the like. Referring to FIG. 1, a conventional, all-metal manifold, available from Kimball Physics, Inc., Wilton, N.H., comprises a cylindrical main body section 120 having an annular base flange 122 adjacent one end thereof. A flanged end port member 124 is mounted on body 120 opposite flange 122, and a plurality of flanged side port members 126 (four are shown for illustration purposes) are mounted equi-spaced around the circumference of body 120 and angled downwardly and inwardly so that imaginary lines running centrally of ports 124 and 126 will converge at a single point (not shown). Each flange 124, 126 includes a plurality of tapped bolt holes 128 for joining similarly sized and shaped flanges carried by other adapters, instruments and/or conduits, while base flange 122 includes a set of tapped holes 130 and a set of clear holes 132, e.g. for mounting the manifold to a chamber or the like. In order to assure a gas-tight connection, the face of base flange 122 and port members 124 and 126 each have an annular recess 134, each having an annular "knife edge" 135 for accommodating and engaging a soft metal gasket material, e.g. in accordance with teachings of U.S. Pat. No. 3,208,758.
Body 120 and port members 124 and 126 typically are formed separately of stainless steel such as type 304 stainless, and are welded together to form a gas-tight construction. Base flange 122 also is formed separately, and may be welded to body 120 in fixed position, or may be rotatably retained on body 120 by means of a rotatable flange retaining ring 123, which in turn is welded to body 120.
While prior art manifolds of the type described above have achieved widespread use and are available commercially from several sources, fabrication is a somewhat difficult and costly process. First, the main body section 120, end port member 124 and side port members 126 are separately machined from round metal stock, e.g. on a metal lathe. Holes 136 (see FIG. 2) are then drilled in main body section 120. The flanged end walls of end port member 124 and side port members 126 are machined flat, holes 128 are tapped therein, and annular recess 134 and knife edge 135 are machined in the flanged end walls of port members 124 and 126. The ends of port members 124 and 126 opposite the flanged end walls of port members 124 and 126 are then machined to fit together with main body section 120, and the port members are carefully positioned and lined-up, e.g. using optical alignment means, and tacked in position by welding. The port members are then finish welded and again checked for alignment. Finally, base flange 122, which also is separately formed, is mounted on rotatable flange ring 123 which in turn is welded to body section 120. As will be appreciated, machining the various parts is expensive and time-consuming. Also, achieving exact alignment of port members 124 and 126 presents a problem. Moreover, end port member 124, which must be made long and thin-walled to provide sufficient clearance for the side port members 126, is mechanically compromised. Consequently, end port member 124 may flex out of alignment should a heavy component or large external force be applied to the end port.
It is thus a general object of the present invention to provide improved methods of manufacturing all-metal manifolds which overcome the aforesaid and other disadvantages of the prior art.
Another object of the present invention is provide an improved method for manufacturing all-metal manifolds having improved performance and reliability characteristics.